The most crucial fields in the validation report for understanding your email verification results when you validate email addresses are Classification and Status.
In the Classification field, there are four well-defined output values:
- Deliverable, meaning the email is considered safe to send;
- Risky, when the email is undesirable or sending to it may result in a bounce;
- Undeliverable, when the email is known to be undeliverable and will likely generate a bounce;
- Unknown, in the rare cases where we couldn't classify the email into any of the other groups.
On the other hand, the Status field can have various values, and we provide general recommendations for most customers for each value listed below.
We highly recommend considering your specific needs when assessing non-definitive or risky results: you have the flexibility to either reject all results that are not labeled as Success or accept some of them.
Generic status codes
Success
Valid email, with no high-risk factors detected: safe to send mail.
Syntax status codes
UnmatchedQuotedPair
Invalid email format: a quoted pair within a quoted word is not properly closed. Quoted words in email addresses refer to portions of the email address that are enclosed within double quotation marks ("): these quoted words are used to include special characters or spaces within an email address's local part (the part before the "@" symbol) that would otherwise not be allowed.
UnexpectedQuotedPairSequence
Invalid email format: an unexpected quoted pair sequence has been found within a quoted word. Quoted words in email addresses refer to portions of the email address that are enclosed within double quotation marks ("): these quoted words are used to include special characters or spaces within an email address's local part (the part before the "@" symbol) that would otherwise not be allowed.
InvalidWordBoundaryStart
Invalid email format: a new word boundary has been detected at an invalid position.
InvalidCharacterInSequence
Invalid email format: an invalid character has been detected in the provided sequence.
UnbalancedCommentParenthesis
Invalid email format: the number of parentheses used to open comments is not equal to the number used to close them. Comments in email addresses are a way to include additional information or annotations within an email address without affecting the functionality of the address.
DoubleDotSequence
Invalid email format: an invalid sequence of two adjacent dots has been found.
InvalidLocalPartLength
Invalid email format: the local part of the email address has an invalid length.
InvalidFoldingWhiteSpaceSequence
Invalid email format: an invalid folding white space (FWS) sequence has been found. Folding white space (FWS) is a concept defined in the Internet email standards (RFC 5322) and refers to the use of white space (spaces, tabs, or line breaks) to format and structure certain parts of an email header, including the message body.
AtSignNotFound
Invalid email format: the "@" symbol, used to separate the local part from the domain part of the address, has not been found.
InvalidEmptyQuotedWord
Invalid email format: an invalid quoted word with no content has been found. Quoted words in email addresses refer to portions of the email address that are enclosed within double quotation marks ("): these quoted words are used to include special characters or spaces within an email address's local part (the part before the "@" symbol) that would otherwise not be allowed.
InvalidAddressLength
Invalid email format: the email address has an invalid total length.
DomainPartCompliancyFailure
Invalid email format: the domain part of the email address does not comply with IETF standards.
IspSpecificSyntaxFailure
Following the syntactic rules of the target mail exchanger(s) for the domain, the address is considered syntactically invalid.
Disposable status codes
DomainIsWellKnownDea
High-risk email type, the address is associated with a well-known disposable / throw-away email provider. A disposable email provider, often referred to as DEA provider, is a service that offers temporary and anonymous email addresses for short-term use.
MailboxIsDea
High-risk email type, the address is associated with a well-known disposable / throw-away email provider. A disposable email provider, often referred to as DEA provider, is a service that offers temporary and anonymous email addresses for short-term use.
MailExchangerIsWellKnownDea
High-risk email type, the address is associated with a well-known disposable / throw-away email provider. A disposable email provider, often referred to as DEA provider, is a service that offers temporary and anonymous email addresses for short-term use.
DNS status codes
DomainDoesNotExist
Invalid email address, the domain does not exist.
DnsQueryTimeout
A timeout occurred while querying the DNS servers for records about the domain. Trying a higher results quality level is likely to provide a definitive response.
DnsConnectionFailure
A socket connection error occurred while querying the DNS servers for records about the domain. Trying a higher results quality level is likely to provide a definitive response.
DomainIsMisconfigured
Invalid email address, the domain lacks valid DNS records and cannot receive messages from external hosts on the Internet..
SMTP status codes
SmtpConnectionTimeout
A timeout occurred while trying to connect to the mail exchanger that serves the email address domain. Trying a higher results quality level is likely to provide a definitive response: if the issue persists, it indicates that the domain associated with the email address is unable to accept email messages.
SmtpConnectionFailure
A socket connection error occurred while trying to connect to the mail exchanger that serves the email address domain. Trying a higher results quality level is likely to provide a definitive response: if the issue persists, it indicates that the domain associated with the email address is unable to accept email messages.
SmtpDialogError
Validation failed because the external mail exchanger replied in a non-standard way. Trying a higher results quality level is likely to provide a definitive response.
LocalEndPointRejected
Validation failed because the external mail exchanger rejected the local endpoint. Trying a higher results quality level is likely to provide a definitive response.
Mailbox status codes
MailboxDoesNotExist
The mailbox for the email address does not exist.
MailboxConnectionFailure
Failed to validate, a connection error occurred while validating the mailbox for the email address. Retrying the validation may result in a definitive response.
LocalSenderAddressRejected
Validation failed because the external mail exchanger rejected the local sender address. Trying a higher results quality level is likely to provide a definitive response.
MailboxValidationTimeout
Validation failed due to a timeout while verifying the existence of the mailbox. Trying a higher results quality level is likely to provide a definitive response.
MailboxTemporarilyUnavailable
Validation failed because the requested mailbox is temporarily unavailable. This doesn't necessarily mean the mailbox doesn't exist; it's often a response from mail exchangers with greylisting enabled. Trying a higher results quality level is likely to provide a definitive response.
ServerDoesNotSupportInternationalMailboxes
Invalid email address: the external mail exchanger does not support international mailbox names. To support this feature, mail exchangers must comply with RFC 5336 and announce support for both the 8BITMIME and UTF8SMTP protocol extensions.
MailExchangerIsHoneypot
High-risk email type: the email address is a honeypot (also known as spamtrap). We strongly advise removing honeypots from your lists.
Catch-all status codes
CatchAllValidationTimeout
Validation failed due to a timeout while verifying the rejection of a fake email address by the mail server. Trying a higher results quality level is likely to provide a definitive response.
ServerIsCatchAll
Possibly risky email type: the external mail exchanger accepts fake and nonexistent email addresses. Therefore, the provided email address may not exist, and the existence of the individual mailbox cannot be verified.
CatchAllConnectionFailure
Failed to validate, a connection error occurred while verifying the catch-all settings on the external mail server. Retrying the validation may result in a definitive response.
Duplicate removal/scrub status codes
Duplicate
The email is a duplicate of another entry that has been previously verified in this list.
Miscellaneous status codes
UnhandledException
Validation failed due to unexpected technical issues during the processing of this email address. Retry may provide a definitive response.